Oxidatively stable alkylbiphenyls and terphenyls as non-spreading lubricants



United States Patent 3,426,076 OXIDATIVELY STABLE ALKYLBIPHENYLS ANDTERPHENYLS AS NON-SPREADING LUBRICANTS Helen Mertwoy, Montgomery, andHenry Gisser, Philadelphia, Pa., assignors to the United States ofAmerica as represented by the Secretary of the Army No Drawing. FiledJuly 28, 1966, Ser. No. 568,680 US. Cl. 260612 2 Claims Int. Cl. C10m3/10, 3/14 ABSTRACT OF THE DISCLOSURE Non-spreading lubricants andfluids which are oxidatively stable at low and high temperatures andcomprising a mono or di-sec-butyl-biphenyl or terphenyl or mono ordi-sec-butyl-methoxybiphenyl or methoxyterphenyl.

This invention relates to fluids and lubricants and more particularlyconcerns new and improved nonspreading fluids which are stable tooxidation.

Many nonspreading fluids are useful as lubricants in applications suchas watch mechanisms, clocks and fuzes where a continual supply oflubricating substance cannot readily be provided and where the lubricantfilm is placed between components having low relative speeds such thatthe resistance of the lubricant to spreading governs the accuracy of themechanism. Since the nonspreading component of such nonspreadinglubricant is an important factorcontributing to the performance of thelubricant, control of the nonspreading ingredient will usually lead tocontrol of the compounded lubricant. Prior art researchers havecompounded lubricants from blends containing a nonspreading ingredientcomprising a dieste-r made from an aromatic alcohol and a dibasic acid,having the general formula:

where X and R are aliphatic (straight or branch chain) groups; X havingup to 4 carbon atoms, R having up to 5 carbon atoms, and M is 5 through7. The lubricant would normally contain a suitable oxidative inhibitor,among other possible additives. Since addition of oxidation inhibitorsto fluids can change the physical properties thereof e.g., freezingpoint, and since aromatic compounds do not respond well to antioxidants,it would be advantageous if a nonspreading fluid which is also stable tooxidation could be provided.

It is therefore an object of this invention to provide improvednonspreading lubricants.

Another object of the invention is to provide improved nonspreadinglubricants which are stable to oxidation up to at least 100 C.

Other objects and features of the invention will become apparent as theinvention is more fully hereinafter disclosed.

In accordance with these objects it has been discovered that a mono ordi-sec-butyl-biphenyl or terphenyl or mono ordi-sec-butylmethoxybiphenyl or methoxyterphenyl will provide anonspreading oxidatively stable fluid. The alkyl group or groups will beattached to the ring through a 3,426,076 Patented Feb. 4, 1969 tertiarycarbon atom. Examples of structures of this type are as follows:

R=sec-butyl, hydrogen, or methoxy R"=sec-butyl or hydrogen m-terphenylSince the higher the symmetry of a substituted biphenyl or terphenyl thehigher the melting point, it is important that the compounds be asunsymmetrical as possible in order to obtain liquids. For example,4,4-di-sec-buty1- biphenyl is a liquid yet 4,4-dibutylbiphen-yl (M.P.58.5 C.) and 4,4'-di-tert-butylbiphenyl (M.P. 128.5 C.) are solids.Therefore, substituted and unsubstituted biphenyls and terphenyls werereacted with sec-butyl chloride to form liquid sec-butyl derivativeswhich were unsymmetrical compounds.

In Table I below, spreading data are presented for our nonspreadingoxidatively stable fluids, the data being obtained at room temperatureunder anhydrous conditions.

TABLE I.SPREADING DATA 1 Evaporated.

Compound is a known spreading fluid and is presented for comparisonpurposes.

Despite the high boiling point of 4-sec-butylbiphenyl (107 C. at 0.7mm.), it completely evaporated within about 4 days leaving no residue onthe disk on which it was being tested. This compound has been founduseful therefore in closed systems. While a drop of 4-sec-butyl-4'-methoxybiphenyl only spreads 0.9% after 30 days, its volume hadnoticeably decreased indicating that this compound (B.P. 146 C. at 0.7mm.) was also evaporating but at a much slower rate.

Spreading of an oil was determined in the following manner: One inchdiameter disks of WD 52-100 steel, hardened to Rockwell C-62, werepolished successively with 0, 2/0, 3/0, and 4/0 emery paper, washedunder wanm tap water while being scrubbed with cotton gauze, then washedwith distilled water followed by redistilled methanol. The disks werethen dried by clean dry air. To

Percent spreading aiter determine cleanliness, a drop of redistilledmethanol was placed on the surface of each disk. Complete and uniformevaporation indicated surfaces acceptable for these tests. A drop of theoil to be tested, 1 to 2 mm. in diameter, was placed on each disk bymeans of platinum wire. The degree of spreading was obtained bymeasuring the change in diameter after 7 and 30 days, respectively,using a traveling microscope.

Our nonspreading fluid may be prepared as follows using4-sec-butyl-4'-methoxybiphenyl and 3,4-di-sec-butyl- 4-methoxybiphenylas examples:

p-Phenylanisole (0.25 mole, 46 gm.) was dissolved in 700 ml. of hothept-ane contained in a 1000 cc. fournecked flask, fitted with astirrer, reflux condenser, thermometer and dropping funnel. Fourteengrams of anhydrous aluminum chloride were then added. The solution washeated, and while maintaining a temperature at 75-85" C., 0.27 mole (25gm.) 2-ch1orobutane was added dropwise over a period of 2.5 hours. Afteraddition was complete, stirring was continued for an additional 5.5hours, the temperature being maintained at 75 -85 C. The reactionmixture was poured over an equal volume of cracked ice and stirredvigorously to decompose the aluminum chloride complexes. The organiclayer was washed free of acid with distilled water. The unreactedp-phenylanisole was removed by distillation using a steam condenser. Theremaining mixture was distilled in a molecular pot still to separate theproduct from solids and tarry products. The liquid was then fractionatedusing a Vigreux column to yield both 4 sec. butyl 4' methoxybiphenyl(B.P. 137 C. at 0.65 mm.) and 3,4 di sec butyl 4' methoxybiphenyl (B.P.162 at 0.75 mm.). Both compounds were then fractionated for furtherpurification using a Vigreux column until the distillation range wasless than 2 C.

In view of the above, a description of the preparation of the othercompounds of our invention will not be presented herein as fallingwithin the knowledge of a skilled organic chemist.

In the table below, some oxidation rates of our inventive nonspreadingcompound are presented. As can be readily observed from the table, thereis very little oxygen uptake even after 100 hours.

TABLE II.OXIDATION RATES AT 100 C.

(Moles Oz/mole compound/hr.) X104 Compound Initial rate Final rateduring 5-35111'. during -100 Oxygen consumption at was measured by usingstandard Warburg manometry. One milliliter of compound was introducedinto the main compartment of the Warburg flask. Since oxygen consumptionin the initial stages of autoxidation was measured, it was not necessaryto use absorbents for volatiles. The flask was immersed in 100 C. oilbath and allowed to come to equilibrium during which time the system wasflushed with oxygen for approximately 15 minutes. When the system wasfinally closed to the atmosphere excess oxygen pressure was bled OK sothat 0.1 to 0.5 cm. of pressure remained. Oxygen consumption wascalculated as moles of oxygen per mole of compound.

We claim:

1. A nonspreading fluid oxidatively stable at elevated temperatures,said fluid being 4-sec-butyl-4-methoxybiphenyl.

2. A nonspreading fluid oxidatively stable at elevated temperatures,said fluid being 3,4-di-sec-butyl-4-methoxybiphenyl.

References Cited UNITED STATES PATENTS 2,161,558 6/1939 Coleman et al.260-612 2,172,391 9/1939 Krase. 2,773,906 12/ 1956 Emerson.

BERNARD HELFIN, Primary Examiner.

U.S. Cl. X.R. 25252, 59; 260-668

